Stereotaxic surgical instrument and method



July 29, 1969 c. D. RAY

STEREOTAXIC SURGICAL INSTRUMENT AND METHOD 4 Sheets-Sheet 1 Filed Dec.13, 1966 INVENTOR;

CHARLES RAY TTQ 557.

July 29, 1969 c. 0. RAY

STEREOTAXIC SURGICAL INSTRUMENT AND METHOD 4 Sheets-Sheet 2 Filed Dec.

35 INVENTOR: CHARLES D. RAY

July 29, 1969 v c. D. RAY 3,457,922

v ESTEREOTAXIC SURGICAL INSTRUMENT AND METHOD Filed Dec. 13, 1966 4Sheets-Sheet 5 QINVENTOR:

CHARLES 0. RAY

y 29, 1969 c. o. RAY 3,457,922

STEREOTAXIC SURGICAL INSTRUMENT AND METHOD Filed Dec. 13. 1966 4Sheets-Sheet.4

INVENTOR: CHARLES D. RAY

United States Patent M 3,457,922 STEREOTAXIC SURGICAL INSTRUMENT ANDMETHOD Charles D. Ray, 601 N. Broadway, Baltimore, Md. 21205 Filed Dec.13, 1966, Ser. No. 601,445 Int. Cl. A61b 17/00 US. Cl. 128303 2 ClaimsABSTRACT OF THE DISCLOSURE A stereotaxic surgical instrument having a'base element of low profile adapted to be secured to the skull by arapid process of nailing including an arm having one end adjustablysecurable to the base including a surgical guiding means pivotallysecured adjacent the opposite end thereof for guiding a surgicalinstrument in which the surgical guide means is provided with anaperture therethrough extending in a general direction perpendicular tothe surface of the skull wherein the axis of the aperture through thepivotable means may be oriented from various adjusted locations with oneor more surgical targets within the skull cavity without relocating thebase element on the skull.

The present invention relates to a new instrument and method ofstereotaxic surgery and implantation of brain electrodes or probes.

In the past, several stereotaxic techniques and instruments have beendeveloped for study and treatment of certain disorders of the brain andassociated structures within the head. For such uses the instrumentsmust be capable of permitting accurate placement of various diagnosticand surgical devices. Most such instruments are awkward, expensive andbulky. Further, their use has been complicated by difficulty inattachment, the presence of index scales, complex protractors orrectangular measuring systems requiring careful manipulation and the useof certain correction factors found to vary in many patients. Even withthe simpler instruments more recently developed, holes up to one inch indiameter must be placed through the scalp and skull in order to attachthe instrument base. Specific anatomical structures are localized withinthe brain by the X-ray visualization of air or certain organic iodinecompounds placed into the major fluid cavities of the brain, theventricular system. From these visualized landmarks the sites ofproposed electrode or probe implantations are determined by measurementand calculation. Such measurements and calculations are generallydiflicult or tedious not only because of the complexity of theinstruments, but also because of distortions and enlargements producedby the X-ray beam.

Further, while such instruments are capable of accurate placement ofbrain devices or probes for temporary or acute use, they are notgenerally designed nor usable for the placement of devices to be left infor a prolonged period. Stereotaxic instruments generally permitimplantation to occur from or through only limited areas of the head inorder to avoid certain critical srtuctures of the brain.

It is a primary object of this invention to provide an improved andsimplified positioning instrument for implantation of brain electrodes,probes and surgical devices.

Another object is to provide precise and convenient universal adjustmentof the instrument.

Still another object of the present invention is to provide a rapid,simple and firm attachment of the supporting base of the instrument tothe skull. This same is performed without the need for holes to beplaced through the scalp Patented July 29, 1969 and bone. In thatexternal contours of skulls show variation among patients, thesupporting base is adaptable to those contours of all human skulls.

A further object of the present invention is to provide a freely movablelocating-guiding assembly that is remotely attached to the supportingbase which is firmly attached to the skull.

Still another object of the present invention is to provide accuratepositioning of the implement prior to drilling of the bone, opening thehead or otherwise penetrating the skull and brain.

A still further object of the present invention is to provide aninstrument for implantation of a brain electrode or probe which permitsthe point of entry and path into the brain to be adjusted prior toimplantation thus avoiding engagement with critical areas thereof. Bythe use of X-rays during positioning, the path of the drill hole is madeaccurately and the end of the electrode or probe can thus be positionedin a desired location. In that the locator assembly lies in the X-raybeam it is therefore subject to the same circumstances as the skull;thus no special correction for X-ray distortion or magnification isneeded.

Ancillary to the preceding object, it is a further object of the presentinvention to provide a probe anchoring device which may be firmly andaccurately placed in the skull. Said anchoring device can be guidedthrough the locating-guiding assembly of the stereotaxic instrument anddriven into place utilizing a special hammer developed for this use.

The above and other objects and advantages of the present invention willbecome apparent in the following descriptions and drawings, wherein:

FIG. 1 is a side perspective view of the instrument constructedaccording to and embodying the present invention;

FIG. 2 is a top plan fragmentary view of the attachment device;

FIG. 3 is an enlarged sectional view taken along line 33 in FIG. 2;

FIG. 4 is an enlarged side fragmentary view of the protra-ctor-pointerassembly partly in section and partly in elevation;

FIG. 5 is a sectional view taken along line 5-5 in FIG. 4;

FIG. 6 is a top plan fragmentary view of the protractor-pointerassembly;

FIG. 7 is a diagrammatic front elevation of the instrument applied to askull;

FIG. 8 is a diagrammatic right-hand side elevation of the instrumentshown in FIG. 7;

FIG. 9 is an enlarged fragmentary sectional view of theprotractor-pointer assembly in place on a skull;

FIG. 10 is a fragmentary sectional view as shown in FIG. 9, the scalpand skull shown being drilled;

FIG. 11 is a fragmentary sectional view as shown in FIG. 9, a slidingweight hammer shown in use to drive a pin into the skull;

FIG. ll-A is an enlarged sectional view of the driver tip and pin; and

FIG. 12 is an enlarged fragmentary sectional view showing a brain probeassembly attached to the pin, wherewith an electrical connector assemblyand an enlarged sectional view of the brain probe are also shown; and

FIG. 12-A is a sectional view taken along the line 12A of FIG. 12.

Referring now to the drawings, particularly FIGS. 1 and 2, referencenumeral 10 generally designates the present instrument which includes atripod base 11 having three foot-plate assemblies 12, and a centrallylocated,

freely movable, compressible ball 13 that can be locked in any positionby a clamping ring 14 having a surface complementary thereto. Throughthe threaded center of this ball 13 is placed a bolt 15 which may betightened against an extension arm 16 thus holding same in some desiredposition. On one side of the extension arm 16 is a removable pointerassembly 17 including a base portion 36, an outwardly extended portion36' and a point 36". Near the distal end of the extension arm 16 is aspherically surfaced concavity which defines a coupling socket intowhich is placed a second freely movable, compressible ball 18. This ball18 and the central ball 13 are formed of a steam autoclavable, X-raytransparent plastic such as polycarbonate or polyphenylene oxide or thelike. Said distal ball 18 rotates in a complementary surface of theouter end of the extension arm 16 and is locked in position bytightening the set screw 19 pinching the ball between the confrontingfaces of the jaw members 16' and 16". Threaded into the axial bore ofthe distal ball 18 is a removable hollow guide bolt 20 onto which isshown attached a spherical protactor assembly 21. The upper surface 34of this protractor 34, in near contact with the tip of the pointer 36",is accurately engraved to indicate angular changes from position 22 to anew position 23 (see FIG. 1).

Referring to FIG. 3 it can be seen that the foot-plate assembly 12consists of a freely movable, drilled singleball bearing 24 whose race25 has been pressed into the tripod base 11. Pressed into the ball 24 isa foot-plate 26. Through the center of same is placed a removablecranial nail 27 having a threaded upper end 27 and a pointed lower end27". The central ball 13 is clamped in desired position by the clampingring 14 by the three set screws 28 placed equidistant around saidclamping ring 14. The central bolt 15 compresses a thrust washer 29against the extension arm 16 and against a spacer 30 thence against thecentral ball 13.

Referring now to FIGURES 4 through 6, reference numeral 17 refersgenerally to the pointer assembly and reference numeral 21 refersgenerally to the spherical protractor assembly. The demountableprotractor assembly 21 is provided with a shaft 31 made of X-raytranslucent aluminum down the center of same is poured a lead core 33being opaque to X-rays. Said shaft 31 is held into place on the bolt 20of the distal ball 18 by a captive nut 32. The protractor proper 34 isfirmly screwed to the shaft 31 and is provided with outer curvedsurface. With 34 the curved outer surface is provided with grid groovesor lines 34", the distal hall 18 in a position with its axial shaft 31perpendicular to the plane of the extension arm, the point C on thesurface of the protractor 34 indicates a central location for theprotractor assembly or neutral zero position as shown in FIGS. 4 and 6.Angular displacements of the ball about its axis from this neutral zeroposition are indicated by the grid grooves or lines as previouslydescribed. The said grid grooves or lines are placed each 2 degrees withheavier grooves at 10 degree spacing. The member 34 of the protractorassembly is made of an X-ray transparent plastic similar to that of thecentral and distal balls 13 and 18. All grid grooves are filled with acured mixture of white lead and epoxy plastic. These grooves are therebyX-ray opaque. The grooves, being established in reference to the centerof rotation of the distal ball 18 exhibit a great circle curvature.

The pointer assembly 17 is demountable from the extension arm 16 bymeans of a captive screw 35 maintained to the pointer arm 36 by apermanently pressed on spacer 37. Two indexing pins 38 are permanentlypressed into the pointer arm 36 base and mate into corresponding holesin the extension arm 16 thus establishing a temporary rigid attachmentto same.

Referring now in particular to FIGS. 7 through 11, the operation of theinstrument is as follows:

The instrument is placed upon the head 39 at a predetermined locationand in turn each tripod foot-plate assembly 12 is anchored to the skullby the driving of a cranial nail 48 or screw or suitable holdingelement. The cranial nail 27 may be screwed into the end of the captivehammer 42 to be so driven. When firmly attached to the head, the tripodbase 11 is rigid with respect to the skull. Set screws 28-and 19 andcentral bolt 15 are made slack so that the positioning of the extensionarm 16 and the distal ball 18 is freely selectable for any point overthe surface of the head 39. The protractor assembly 21 is attached intothe guide bolt 20 within the distal ball 18 and made fast by tighteningthe captive nut 32 provided. The pointer assembly 17 is then attached tothe extension arm 16 and made fast utilizing the captive screw 35 andindexing pins 38. A first approximation path 22 of the final desiredpath 23 to the brain target 40 is made and all set screws 19 and 28 aretightened such that no motions of the present instrument are nowpermitted save a sliding friction movement of the distal ball 18 andprotractor assembly 21.

The major reference cross lines on the spherical surface of theprotractor 34 are adjusted to lie exactly parallel and perpendicular tothe front-to-back center line of the skull. Adequate X-ray contrastmedium is instilled into the brain cavities or ventricles 41 and theproposed target site 40 is exactly determined based on requirements ofthe operative case.

A carefully positioned front-to-back, or anterior-posterior X-ray filmis taken as shown diagrammatically in FIG. 7. In a similar manner sameis performed for a lateral film as in FIG. 8. Close examination of saidfilms will disclose the correct path 23 to be taken. A line is drawnupon the surface of the X-ray film extending from the target siteoutward through the center of the distal ball 18 and beyond thencethrough the protractor 34. The central lead core 33 of the protractorshaft 31 and individual lead-filled surface grooves 34" of theprotractor 34 are clearly visible on the X-ray film as showndiagrammatically in FIG. 9, thus permitting an accurate angularcorrection to be determined for both anterior-posterior and lateralplanes. The protractor assembly 21 and distal ball 18 alone arecarefully moved so as to correspond to the desired path 23 to the braintarget 40. Following this, recheck or confirmatory X-ray films may betaken in the two planes. The set screw 19 holding the distal ball 18 isnow firmly tightened. No further movements of the instrument 10 relativeto the head 39 may now be permitted. Both the pointer assembly 17 andprotractor assembly 21 are now removed.

As is shown diagrammatically in FIG. 10, a drill is passed through theguide bolt 20 and thence penetrates scalp and bone of the head 39 in thedesired path 23.

Referring now to FIG. 11, a captive hammer is generally referred to bythe numeral 42 and comprises a shaft 43 onto one end at which is affixeda stop piece 44 having a threaded hole therein. On the opposite end ofsaid shaft 43 is a grasping handle 45. A freely sliding weight 46 maythus be slid axially along the shaft 43 to engage or strike the stoppiece 44 or the face of the handle 45. In the use described herein a pininserter 47 is screwed into the stop piece 44. The distal end of thisinserter 47 is so fabricated to pass into the core hold of the cranialpin 48 and thus made to drive said pin through the guide bolt 20 axiallyinto the hold previously drilled into the skull 39. A diametric step 48'in the cranial pin 48 stops it at a desired length into the bone of theskull 39.

In that the cranial pin 48 has been positioned in the desired path 23 tothe brain target 40, the entire instrument 10 may be moved elsewhereupon the head or removed entirely. If so desired the present instrumentmay be utilized for temporary or acute implantation so that no cranialpin 48 need be placed.

Referring now to FIG. 12 a brain probe is referred to generally by thenumeral 50 and its mating electrical connector socket by the numeral 58.Said probe 50 consists of a central tube 51 having a hollow core 52 andaround said tube are suitably cemented a plurality of fine wires 53previously insulated for their entire length. Said wires 53 are attachedto the end of a suitable electrical connector 55 comprising one of samefor each wire used in the probe. This assembly is then encapsulated thusinsulating the terminations between wires 53 and connectors 55. Afterfabrication of the probe device a suitable contact 56 is established ata singular, selected location .by removing the insulation from the wireat that point. Said probe 50 has been previously disclosed and is notpresented as a part of the present invention.

The probe or other such device is maintained on the head for prolongedimplantation thusly: onto the threaded end of the cranial pin 48 isscrewed a retaining cup 49, into same is then placed the probe 50 orother such device. Same is held firmly in place and is prevented frommovement by a locking ring 57 whose inner surfaces are suitably disposedto seal the probe 50 against the retaining cup 49. Said probe 50 is ofsufficient length to reach the brain target 40. An electrical connectorsocket assembly 58 may be mated with the probe at such time asdiagnostic studies are to be performed.

The captive hammer 42 is used both to drive and remove the cranial nails27 and the cranial pins 48. Same may be implanted with or without theuse of a pin inserter 47. A rapid sliding of the weight 46 transmits itsforce axially into or away from the implanted piece depending on thedirection of slide and end struck.

It will be appreciated that there is herewith illustrated and describedan instrument which may be easily attached to the skull, permittingexact determinations of paths to be taken for inmplantation of devicesfor temporary or prolonged study or treatment of selected targets withinthe brain utilizing landmarks determined by standard X-ray film.

Variations and modifications may be made without departing from thespirit of this presentation of a preferred embodiment of the presentinvention.

I claim:

1. A stereotaxic instrument for use with an X-ray machine to locate atarget area within a skull cavity having a base adapted to be fixed tothe skull and supporting thereon an adjustable pivot means includingmeans for fixing the position of the pivot means relative to the basecomprising in combination:

(a) an elongated arm having an end portion releasable fixedly to saidpivot and longitudinally adjustable relative to said pivot, and meansfor locking the arm at selected positions;

(b) means on said arm positioned outwardly from said first pivot meansfor engaging a second pivot means, and means for fixing the position ofthe second pivot means relative to the arm;

(c) the second pivot means having a guideway associated therewith;

(d) an X-ray transparent removable protractor assembly including a stemconstructed of X-ray trans parent material adapted to have one endslidably engageable and removable with the said guideway of the secondpivotable member and a disk-like member fixed to the opposite end of thestem, the outer surface of the disk-like member being provided with gridlines of X-ray photographic material;

(e) an X-ray photographic material extending along said grid lines andalong said stern;

(f) an opaque stationary pointer afiixed to the said arm and extendingover the grid surface of the disk and in close proximity thereto;whereby the position of the pointer on the grid surface may be recordedon an X-ray picture along with the angle of the stem in its relation tothe target area in the skull cavity.

2. A method of determining the direction and course of a brain probetoward a target area within a skull cavity, from outside the skull, inwhich an adjustable, fixable support including a fixed pointer isutilized to support a pivotable and fixable-holding member having aguideway associated therewith for a directional indicating means forindicating the path of the probe, wherein the directional indicatorconsists of an X-ray transparent removable protractor assembly includinga stern constructed of X-ray transparent material having a photographiclongitudinal line extending therealong adapted to have one end engagablewith the guideway of the holding member and a disk-like member having anouter surface provided with grid lines thereon corresponding to theangle of the protractor relative to the center line thereof and fixed tothe opposite end of the stem, wherein said grid lines are X-rayphotographic, comprising the steps:

(a) securing the support to the skull;

(b) fixing the holder for the protractor assembly at a predeterminedpoint over the outer surface of the skull;

(c) inserting the stem of the protractor assembly into the guideway ofthe holder;

(d) aligning the pointer with a predetermined pair of I intersectinggrids;

(e) making an X-ray film of the entire assembly, showing both protractorand desired point within the skull cavity;

(f) extending the photographic line of the stern on the film to a pointindicating the inward portion of the skull cavity;

(g) extending a line on the film through the pivot point of theprotractor assembly holding means and the target area;

(h) determining the angle between the two lines extending outwardly fromthe holding means, noting the points where the lines extend through thegrid marks as shown on the X-ray film;

(i) readjusting the protractor assembly by using the grid lines formedon the disk to represent the number of degrees between the inverginglines on the film;

(j) making a verification X-ray film;

(k) removing the protractor assembly from the holder guideway;

(l) inserting a drill tool within said guideway in the holder anddrilling an opening in the skull along the axis of the said guideway ofthe holder;

(m) removing said drill and insreting a tool along the said guidewayhaving a probe guide element detachably secured thereto, forcing thesaid probe guide element into said skull opening along the axis of theguideway, detaching said tool, inserting said probe and extending thesame beyond the said probe guide element into the skull cavity andtoward the target area.

References Cited UNITED STATES PATENTS 3,073,310 1/1963 Mocarski 128-3033,357,431 12/1967 Newell 128303 L. W. TRAPP, Primary Examiner

